I'm not sure I buy that - Humans can create meaning out of everything - You do not need children for that (there are some that spend years meditating in literal caves and claims that their life is also full of meaning).

So given that we can have two persons with life full of meaning, one of which is feeling down most of the time, and both of them somehow selected this life for themselves - its not quite hard to point at not having children as a better way of life. I speak of course from the point of view of me/solicity - others should have as many children as it is required to keep my precious useless stuff mass produced overseas to keep numbing consumptionism continuing until nothingness takes me back.